HD 7950 prblem !!

Hello everybody,

yesterday i installed a new ati radeon HD7950..... everything seems to be perfect after installing... later while playing games like BF3,AC3 and far cry 3 it seems to flicker.. weird horizontal lines can be seen. i even updated my drivers.. still of no use.. tried installing like 5 or 6 times... but one thing my monitor i mean the display there is no problem like flickering...please help  

my specs:
cpu: amd phenom 2 X4 965 BE
psu:850tx corsair
gpu:sapphire HD 7950
monitor:acer V199HQV

thank you !